[R] lsmeans

hadley wickham h.wickham at gmail.com
Sun Jun 8 01:04:50 CEST 2008

On Sat, Jun 7, 2008 at 3:02 PM, John Fox <jfox at mcmaster.ca> wrote:
> Dear Dieter,
> I don't know whether I qualify as a "master," but here's my brief take on
> the subject: First, I dislike the term "least-squares means," which seems to
> me like nonsense. Second, what I prefer to call "effect displays" are just
> judiciously chosen regions of the response surface of a model, meant to
> clarify effects in complex models. For example, a two-way interaction is
> displayed by absorbing the constant and main-effect terms in the interaction
> (more generally, absorbing terms marginal to a particular term) and setting
> other terms to typical values. A table or graph of the resulting fitted
> values is, I would argue, easier to grasp than the coefficients, the
> interpretation of which can entail complicated mental arithmetic.

The other advantage is that the effects values are on the same scale
as the original data, and it can be useful to supplement the pure
effects with the original data.



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